A hot, dry climate, with arable land. When a river passes through an arid region, the silt on the riverbanks has a fertility of 6. The rest of the region fluctuates between 2 and 3 fertility. Papyrus can sometimes be found in arid regions, however Papyrus cannot be cultivated in Arid regions.
The Arid biome is heavely affected by the presnece or absence of water, since an arid tile with water will have fertility 6 present directly adjecent to the water and a larger cloud of fertility 3 surrounding it. getting an arid tile with water is a lot more valuble then an arid tile without water. wood often is lacking in arid biomes so it would be advisable to get a wood outpost in another biome.